Death Finds a Way: A Janie Riley Mystery by Lorine McGinnis Schulze. Janie Riley is an avid genealogist with a habit of stumbling on to dead bodies. She and her husband head to Salt Lake City Utah to research Janie's elusive 4th great-grandmother. But her search into the past leads her to a dark secret.
A: The most abundant isotope of magnesium has 12 neutrons; it is therefore, technically known as magnesium-24. Calculating the number of neutrons in an isotope of any element involves subtracting that element's atomic number from its atomic weight. Magnesium's number is 12, and its weight is just over 24.
All isotopes of an element will always have the same number of protons. The UPPER number represents the MASS NUMBER, which is number of protons PLUS number of neutrons. This is unique for every isotope. Magnesium 24 has 12 neutrons, Magnesium-26 has 14 neutrons and Magnesium-30 has 18 neutrons.